Validating the Concept of COPD Control: A Real-world Cohort Study from the United Kingdom

Figures & data

Table 1. Measures used to evaluate baseline control as defined by Soler-Cataluña et al. (10) and the database proxies used in the study.

		Mild–to-moderate severity; BODEx ≤ 4 points		Severe/very severe COPD; BODEx ≥ 5 points
Components of baseline control		Proposed definition component	Proxy used	Proposed definition component	Proxy used
IMPACT	Dyspnoea	mMRC score 0–1	mMRC score 0–1	mMRC score 0–2	mMRC score 0–2
	Rescue medication	≤3 times in the last week	Score of ≤ 3 to the following OPC COPD question:	≤2 times a day	Score of ≤ 4 to the following CAT question:
			0 = “I don't need to take my inhalers regularly”		0 = “I don't need to take my inhalers regularly”
			5 = ”I need to take my inhalers regularly”		5 = ”I need to take my inhalers regularly”
	Daily physical activity	≥60 min walking/day	Score of ≥ 5 in response to the question: “Thinking about exercise, how much time do you exercise/activity (e.g. walking)”	≥30 minutes walking/day	Score of ≥ 3 in response to the question: “Thinking about exercise, how much time do you exercise/activity (e.g. walking)”
			1 = No exercise, 2 = 15 minutes, 3 = 30 minutes, 4 = 45 minutes, 5 = 60 minutes,s 6 = 120 minutes, 7 = ≥180 minutes		1 = No exercise, 2 = 15 minutes, 3 = 30 minutes, 4 = 45 minutes, 5 = 60 minutes, 6 = 120 minutes, 7 = ≥180 minutes
	Sputum colour	Absent or white	Score of < 4 to the following CAT question:	Absent or white	Score of < 4 to the following CAT question:
			0 = “I have no phlegm (mucus) on my chest at all”		0 = “I have no phlegm (mucus) on my chest at all”
			5 = My chest is completely full of phlegm (mucus)		5 = My chest is completely full of phlegm (mucus)
	OR
	CAT	≤10	<10	≤20	≤20
AND
Stability	Exacerbations	None	0 exacerbations between months −3 to 0	None	0 exacerbations between months −3 to 0

Figure 1. Patient selection flow diagram showing identification of the study cohort following application of the study inclusion/exclusion criteria.

Figure 2. Evaluation of Control within the study population. (A) Flow diagram showing the number of patients within the mild/moderate COPD cohort with controlled/uncontrolled COPD, split by (i) Clinical-Feature-defined low impact (ii) CAT-defined low impact. (B) Flow diagram showing the number of patients within the severe/very severe COPD cohort with controlled/uncontrolled COPD, split by (i) Clinical-Feature-defined low impact (ii) CAT-defined low impact.

Table 2. Baseline demographics and clinical characteristics by COPD Control definition and resultant control status for patients with Mild/Moderate COPD, stratified by clinical features/CAT scores.

Patient Characteristics			Low impact, by clinical features		Low impact, by CAT Score
		BODEx ≤ 4	Controlled	Uncontrolled	Controlled	Uncontrolled
Demographics		(n = 2511)	(n = 112)	(n = 2399)	(n = 541)	(n = 1970)
Age (years), Mean (SD)		71.1 (9.5)	69.3 (8.6)	71.2 (9.5)	70.7 (8.8)	71.2 (9.7)
Sex, male; n (%)		1465 (58.3)	65 (58.0)	1400 (58.4)	318 (58.8)	1147 (58.2)
BMI (kg/m^2), Mean (SD)		27.7 (5.8)	26.4 (4.5)	27.8 (5.8)	26.9 (5.2)	28.0 (5.9)^*
Active smokers, n (%)		727 (29.0)	44 (39.3)	683 (28.5)^*	161 (29.8)	566 (28.7)
Comorbidities	Asthma^*, n (%)	732 (29.2)	15 (13.4)	718 (30.0)^*	156 (28.8)	578 (29.3)
	Cardiovascular disease^^, n (%)	992 (39.5)	38 (33.9)	954 (39.8)	189 (34.9)	803 (40.8)^*
FEV1 (%)		62.7 (18.6)	72.3 (19.5)	62.3 (18.4)^*	66.2 (18.8)	61.7 (18.4)^*
CAT Score		16.4 (7.6)	10.2 (5.2)	16.7 (7.4)^*	7.6 (2.0)	18.8 (6.7)^*
mMRC		2.4 (1.0)	1.5 (0.5)	2.4 (1.0)^*	1.7 (0.8)	2.6 (1.0)^*
Rescue medication		3.9 (1.2)	1.6 (0.5)	4.0 (1.1)^*	3.3 (1.3)	4.0 (1.1)^*
Physical activity		3.6 (1.8)	5.9 (0.8)	3.5 (1.8)^*	4.3 (1.8)	3.4 (1.8)^*
Sputum colour		2.0 (1.4)	1.3 (1.2)	2.0 (1.5)^*	1.0 (1.0)	2.3 (1.4)^*

Definitions for assessing low impact with Proxy questions in Table 1. ^*Asthma was defined as a diagnostic Read code for asthma.

^ Cardiovascular disease was defined as a diagnostic Read code for cardiovascular disease.

^* p < 0.05.

Table 3. Baseline demographics for patients with Severe/Very Severe COPD, stratified by clinical feature/CAT score assessment of COPD impact and resultant control status.

Patient characteristics			Low impact, by clinical features		Low impact, by CAT Score
			Controlled	Uncontrolled	Controlled	Uncontrolled
Demographics		BODEx ≥ 5 (n = 277)	(n = 0)	(n = 277)	(n = 23)	(n = 254)
Age (years), Mean (SD)		72.0 (8.8)	0 (0)	71.9 (8.8)	75.1 (8.8)	71.7 (8.8)
Sex, male; n(%)		165 (59.6)	0 (0)	165 (59.6)	15 (65.2)	150 (59.1)
BMI (kg/m^2), Mean (SD)		26.3 (6.6)	0 (0)	26.3 (6.6)	26.5 (7.6)	26.3 (6.5)
Smoking status		79 (28.5)	0 (0)	79 (28.5)	5 (22.0)	74 (29.0)
Comorbidities	Asthma, n (%)	99 (35.7)	0 (0)	99 (35.7)	4 (17.4)	95 (37.4)
	Cardiovascular disease, n (%)	130 (46.9)	0 (0)	130 (46.9)	7 (30.4)	123 (48.4)
FEV1 (%)		35.5 (15.8)	0 (0)	35.5 (15.8)	32.9 (19.6)	35.7 (15.4)^*
CAT Score		26.1 (7.6)	0 (0)	26.1 (7.6)	17 (4.5)	26.9 (7.3)^*
mMRC		4.4 (0.7)	0 (0)	4.4 (0.7)	4.4 (0.5)	4.4 (0.7)
Rescue medication^*		4.6 (0.8)	0 (0)	4.6 (0.8)	4.2 (1.1)	4.6 (0.8)^*
Physical activity^^		2.5 (1.7)	0 (0)	2.5 (1.7)	2.9 (1.7)	2.5 (1.7)
Sputum colour		2.8 (1.6)	0 (0)	2.8 (1.6)	1.2 (1.4)	2.9 (1.5)^*

Definitions for assessing low impact with Proxy questions in Table 1. ^*Asthma was defined as a diagnostic Read code for asthma.

^{^} Cardiovascular disease was defined as a diagnostic Read code for cardiovascular disease.

^* p < 0.05

Table 4. Time to first exacerbation according to control status (by clinical symptom or CAT scores) in patients with different degrees of severity using two different BODEx thresholds (4 and 2 units).

Mild/Moderate COPD: BODEx ≤ 4
Impact/control assessed by:		Clinical features		CAT score
		Controlled	Uncontrolled	Controlled	Uncontrolled
Baseline control status		(n = 112)	(n = 2,399)	(n = 541)	(n = 1970)
Patients with exacerbation	N (%)	23 (20.5)	999 (41.6)	126 (23.3)	896 (45.5)
Time to first exacerbation	Mean (SD) days	176.3 (93.6)	132.7 (98.2)	155.0 (98.9)	130.7 (97.9)
	p-value^*	<0.001		<0.001
Severe/Very severe COPD: BODEx > 4
Impact/control assessed by:		Clinical features		CAT score
Baseline control status		Controlled (n = 0)	Uncontrolled (n = 277)	Controlled (n = 23)	Uncontrolled (n = 254)
Patients with exacerbation	N (%)	0	168 (60.6)	15 (65.2)	153 (60.2)
Time to first exacerbation	Mean (SD) days	NA	114.4 (94.9)	132.1 (100.9)	112.7 (94.5)
	p-value^*	NA		0.587
Mild/Moderate COPD: BODEx ≤ 2
Impact/control assessed by:		Clinical features		CAT score
Baseline control status		Controlled (n = 103)	Uncontrolled (n = 1687)	Controlled (n = 484)	Uncontrolled (n = 1306)
Patients with exacerbation	N (%)	21 (20.4)	606 (35.9)	112 (23.1)	515 (39.4)
Time to first exacerbation	Mean (SD) days	175.3 (92.1)	137.0 (98.8)	157.6 (100.4)	134.1 (97.9)
	p-value^*	<0.001		<0.001
Severe/Very severe COPD: BODEx > 2
Impact/control assessed by:		Clinical features		CAT score
Baseline control status		Controlled (n = 20)	Uncontrolled (n = 978)	Controlled (n = 254)	Uncontrolled (n = 744)
Patients with exacerbation	N (%)	6 (30.0)	557 (56.9)	123 (48.4)	440 (59.1)
Time to first exacerbation	Mean (SD) days	186.0 (151.3)	122.5 (96.5)	134.4 (91.1)	119.5 (98.0)
	p-value^*	0.587		0.492

^* Cox Regression analysis.

Figure 3. Survival curves obtained from Cox regression analysis of the time to first COPD exacerbation over the year following COPD Control assessment, stratified by baseline control status.

Table 5. Percentage of patients that failed to meet the threshold for control for each disaggregated component of low impact, split by COPD severity.

Clinical characteristics	Mild/moderate COPD (BODEx ≤ 4) (n = 2511)	Severe/very severe COPD (BODEx > 4) (n = 277)
Dyspnoea (mMRC)	39.3	90.0
Rescue medication	75.4	92.8
Daily physical activity	19.8	76.5
Sputum colour	15.7	38.3
CAT score	74.8	74.4

Definitions for assessing low impact with proxy questions in Table 1.

Juniper EF, O'Byrne PM, Guyatt GH, Ferrie PJ, King DR. Development and validation of a questionnaire to measure asthma control. Eur Respir J. 1999; 14:902–907.

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